I think what makes a good artist has a lot to do with observation. So I always try (whenever I have the time) to try and do some life drawings because it requires a lot of attention to detail. Your eyes are like muscles, the more you use it the easier and better you get at it, so life drawing almost acts like exercise for your eyes.
Here is a collage of features of several different women I just found randomly on the internet and quickly drew some sketches to learn more about their features and what makes them look real.
I used a dark brown pencil crayon on just a regular sketch book. The reason why I chose to go with a pencil crayon of all things is mainly I didn't have a dark pencil lying around.... It keeps the page clean and wouldn't smudge over time, and its dark color allows a higher level of contrast. The down side is making mistakes are hard to correct... BUT since they were just quick sketches it didn't really bother me that much.